(1) Field of the Invention
The invention relates to a subsea pipeline system for connecting two hydrocarbon production, storage and/or processing structures.
(2) Description of the Related Art
From WO 99/62762, in the name of the applicant, a submerged transfer pipe system is known for transfer of hydrocarbons between two floating offshore structures at sea level. The known transfer pipe system comprises a horizontal duct section, which may have a length of 1000 m or more, suspended from inclined vertical duct sections on each of the respective offshore structures (SPAR buoy, FPSO, export buoy, etc.). A tensioning weight, or tensioning cable connected to the sea bed, is connected near the flexible joints connecting the vertical an horizontal duct sections, such that a tensioning force is exerted on the horizontal duct which prevents buckling or bending and which reduces horizontal displacements due to currents acting on the horizontal duct section.
The known pipeline structure is particularly suitable for use in mid-depth waters such as depths of 50-500 m.
It is an object of the present invention to provide a transfer pipe system which is suitable for use on an irregular seabed.